The invention relates to liquid crystal display, and in particular, to an inversion method for liquid crystal display.
FIG. 1 shows a conventional liquid crystal display 100. Polarity inversion is a technique used in flat panel display to eliminate image retention caused by longtime DC biasing. The liquid crystal display 100 comprises a pixel array 102, a plurality of source drivers 104, and a plurality of gate drivers 106. The source driver 104 is driven by the timing controller 108 to output data signals, and the gate driver 106 outputs scan signals, thereby the pixel array 102 is driven to display images. Each of the source drivers controls a plurality of pixel columns, and each of the gate drivers controls a plurality of pixel lines, thus forming intersecting sections. The timing controller 108 provides inversion signals POL(1H) or POL(2H) to the source driver 104 for determining polarity of corresponding pixels. The source driver 104 thereafter generates data voltage of corresponding polarity accordingly to drive the pixels. The value of inversion signals varies with time, thus polarities of adjacent pixels are different. More specifically, polarities of adjacent pixels are at an opposite level. The inversion signal POL(2H) represents a period twice than that of inversion signal POL(1H). Symbols “+” and “−” denotes polarities of each section in one frame time. The polarity inversion, however, induces certain disadvantages. For example, when the image comprising a specific pattern is input, screen flicker occurs. The specific pattern is referred to as a Killer pattern, caused by panel resistance irregularity, and is unavoidable.
FIG. 2 is a timing chart of an inversion signal POL in the conventional liquid crystal display of FIG. 1. “GCK” denotes the scan line clock. The inversion signal POL(1H) periodically inverts every scan line, and the inversion signal POL(2H) every two scan lines. The inversion may resolve the Killer pattern of FIG. 1, however, another specific pattern can be found to induce screen flicker for the double period case. Thus periodic inversions always present a weakness.